According to the High-Definition Multimedia Interface (HDMI 1.4) Technical Specification, an HDMI Source (source) determines the pixel encoding and video format of a signal transmitted based on: the characteristics of the source video; the format and pixel encoding conversion possible at the source; and the format and pixel encoding capabilities and preferences of an HDMI Sink (sink). The video pixels transmitted across a wired link (cable) are in one of the three different pixel encodings: RGB 4:4:4, YCBCR 4:4:4 or YCBCR4:2:2.
HDMI sources and sinks are capable of supporting RGB 4:4:4 pixel encoding. HDMI sources support either YCBCR 4:4:4 or YCBCR 4:2:2 pixel encoding whenever an HDMI source is capable of transmitting a color-difference color space across any other component (analog or digital video interface), except where the HDMI source would be required to convert RGB video to YCBCR. All HDMI sinks are capable of supporting both YCBCR 4:4:4 and YCBCR 4:2:2 pixel encoding when an HDMI sink is capable of supporting a color-difference color space from any other component analog or digital video input. If an HDMI sink supports either YCBCR 4:4:4 or YCBCR 4:2:2, then both are supported.
HDMI sources and sinks support color depth of 24 bits per pixel, but may support “Deep Color” 30, 36 and/or 48 bits per pixel. All Deep Color modes are optional though if an HDMI source or sink support any Deep Color mode, it supports a 36-bit mode. For each supported Deep Color mode, RGB 4:4:4 is supported and optionally YCBCR YCBCR 4:4:4 may be supported. YCBCR 4:2:2 is also a 36-bit mode. All HDMI sources do not send a Deep Color mode signal to a sink that does not indicate support for that mode.